Exposing-table.



H. C. KNUDSEN.

EXPOSING TABLE.

APPLICATION FILED $514.25, 1911.

PatentedAug. 24, 1915.

3 SHEETS-SHEET .1.

I Fgz, 39 39 H. 0. KNUDSEN.

EXPOSING TABLE.

APPLICATION FILED SEPT.25,1911.

3 SHEETSSHEET 2.

Patented Aug. 24, 1915' wwwmz I9 I I Svwentoz (7%;

H. C. KNUDSEN.

EXPOSING TABLE.

APPLICATION FILED SEPT. 25. I91 1.

1,151,477. Patented Aug. 24, 1915.

3'SHEETSSHEET 3.

Q vi/mmo: 5] W00 ntoz HUGO C. KNUDSEN, 0F BROOKLYN, NEW YORK.

ExrosING-TABLE.

w I specification.

The invention relates to exposing tables for use in making prints upon alight sensitive surface by the action of'light wherein contact is made or perfected by atmospheric pressure, and more especially to' making an impression by means of a light transmitting flexible negative or other design bearing member on a metal or other plate or sheet having a light sensitive surface.

Objects of the invention are to provide for perfect contact b atmospheric pressure between all parts 0 a negative or design carrying element and a plate or sheet having-a sensitive surface upon which the design'from' such negative or element is to be I -impressed by the action of light; more especially to provide perfectcontact by atmospheric pressure between a relatively rigid metal plate or sheet, having a more or less irregular surface and a flexible negative or design sheet during the impression of the picture or design-upon the sensitized surface of such plate or sheet; to provide against formation-of wrinklesor air pockets between the flexible negative or design sheet and the metal plate; to provide for the easy removal of such wrinkles or air pockets in case there is a tendency toward theirformation at first; to provide for a uniform action of the vacuum throughout; and to provide other objects of invention will in part be, jobvious and will in part more fully appear a generallysuperior and useful novel construction of exposing table. These and herein.

The invention consists 1n the novel constructions, arrangements, manufactures,

parts, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein, and forming a part of this specifica-- tion, illustrate one embodiment of the invention, the same serving in connection with the description herein to explain the principles of the invention.

Of the drawings; Figure 1 is a front elevation of an exposing table constructed in accordance with the principles of the in- Spe'cification of Letters Patent.

Patented Aug. 24, 1915.

vention, the clampin frame being shown in elevated position as in Fig. 3) for the sake of clearness; Fig. 2 is a section view, showing particularly theconstruction of the supporting table, and the connection to the yacuum pump; Fig. 3 is an elevation looking at Fig. 1 from the right; Fig. 4 is afragmentary sectional view, on an enlarged scale, on the line AB of Fig. 3, but showmg the clamping frame down and with a printing plate, negative, and the air conveying (or pervious)- and non-air conveying (or lmpervious) coverings in position, that 1s, showing these elements by way of' example as used in making a printing plate; Flg. 5 is a similar viewto Fig. 4 but showing a different supporting means for the plate, comprising a perforate metal sheet or layer; and Fig. 6 is a similar view showing the perforate metal sheet or layer stretched over a layer of felt.

Referring by way of example to the illustrated embodiment, a support of suitable form for the exposing table is provided, and as shown comprises uprights 1 and 2-supported on base pieces 3 and 4, the exposing table being journaled upon said uprights l and 2. For convenience the base pieces 3 and 4 may be supported on casters 5. Angle right 1 and the base piece 3, and similar braces are provlded between the upright 2 braces 6 and 7 are provided between the upand the base piece 4, the angular brace 8 appearing in Fig. 1 of the drawings. Cross frame pleces or braces 9 and 10 are used to connect the uprights 1 and 2. Journaled upon the uprights 1 and 2, by means of pintles or trunnions 15 and 16, is the exposing table, comprising a rectangular frame con sisting of the members 17, 18, 19 and 20 suitably 'JOIIIGd together. The supporting portion of the exposing table may be constructed of any suitable rigid material, and

preferably strips of rubber 24. These extend all the way around on the top of the frame and form with the clamping frame, or sealingdevices on the'clamping frame, when in its-closed position, an air tight o1nt.

The clamping frame is preferably hinged to the frame of the exposing table proper.

As embodied it comprises four rectangular frame members 30, 3 1, 32, and 33 connected to the exposing table along the member 32 by hinges 34. v A resilient sealing member on the clamping frame, to cooperate with the sealing member 24 on the exposing table frame, is provided, and is shown as a strip 36 of rubber carried on the under surface of .the members of the clamping frame, so that when the clamping frame is down and ble frame and the clamping frame are.pro-

vided and as shown herein comprise threaded rods'37, pivotedto the table frame, and carrying nuts 38 adapted to fit into brackets 39 on the clamping frame.

Suitable means for holding the clamping frame in an elevated position are provided and are shown as comprising one or more curved and notched bars 40 pivoted at 41 on the clamping frame each working in an orice in a member 42 fixed on the table frame, and'the notches on the bar adapted to engage with the upper edge of the member 42 i or design to support the clamping frame in its elevated position. Means of suitable or convenient form are also provided for inclining desired, and for p-ree} venting movement thereof by reason of the exposing table as changes in the center of gravity, due to the elevation of the clamping frame or other causes. The illustrated form of such means comprises a curved bar 43 having both ends thereof fixed to the side frame of the exposing table, and having a clamping screw 44 carried by one of the uprights 1- or 2 to hold it in position. i

For the purpose of bringing the negative sheet and the sensitized surface of the plate into absolute contact in all parts thereof despite the inevitable unevennesses and irregularities in the surface of the plate,

means are provided whereby the negative and plate are pressed together uniformly through the entire area thereof by atm0spheric pressure exerted upon a flexible impervious sheet (that is, non-air transmitting) which is clamped between the-frames of the exposing table andclamping frame and sealed by the sealing members, the sensitized ble, and the negative in contact with the sensitized surface of the plate beneath said .impervious'fiexible sheet (Fig. 4).

Means are provided by the invention for plate being supported upon thetapermitting the transverse-travel or'seepage of the air between the negative and the impervious flexible light transmitting element press the negative against the which acts to plate. As embodied this consists of a layer of light-transmitting, porous (that'is, air

conducting) material interposed between said light conducting impervious element and the negative. Thus, the impervious elementmay press closely against all parts of the negative, the pressure being transmitted by the interven ng pervious element, and at,

the same time as the vacuum increases the residual or gradually rarefying air may pass out or travel parallel to the surface of thus insuring per surface of the plate the plate and negative, fec't contact all over the and despite the inevitable: small irregularities in the surface of the plate. The impervious flexible sheet cannot in the early stages of the rarefying or vacuum creating process be pressed tightlyvagainst the edges of the negative seal the area above the plate and prevent further rarefaction there; Also, when the suction device is acting a continuing uni: form condition of pressure is maintained on all the parts of the surface of the plate. Thus a uniformly sharp and perfect imand plate, and thus tend to pression'is made allover the plate by the action of the light through the'negative or design carrying sheet.

As a part of the supporting means for the plate there is included beneath the plate a supporting member of the requisite firmness, but being also'pervious to air, so that it may form a firm support for the plate and at the same'time permitthe air to pass out when. the air exhausting means is beneath the plate as in the embodied form. In Fig. 5 this support is shown asa foram inous metal sheet or layer 56 which may be of interwoven ,wire or other suitable construction,

sufficiently fine to afford a solid support for the plate 51, while the air will pass easily there-'- through. In Fig. 4 a layer offelt50 is shown as such air This layer will be of hard andfirm texture but will also be pervious to the air. In Fig.

' 6 alayer of wire netting or stamped metal 56 is shown stretched over a layer 50 of felt for supporting the plate 51.. On this supporting means igs. .4 and 5) is shown a.

transmitting support.

metal plate 5l-having its upper surface light sensitive, and on this a flexible negative 52. The layer 53 of pervious material is shown above the negative and over'this layer'of 1 pump or other suitable device (not shown) connected by a conduit 55 through the table, thus communicating with the inclosed space between the table and the impervious member 5i and the sealing members 24 and 36. I prefer also that the layer of felt or like material be imperforate over the opening of the conduit 55, for by reason of the porosity of the layer 50 the air seeps or travels therethrough, and the vacuum is created just the same, while the layer 50 prevents the formation of a slight cup or depression in the plate 51 just over the opening of the conduit 55, to thus destroy the contact at that point. It will be understood, therefore, that an air tight area or space is formed between the impervious flexible sheet 54, the sealing members 24 and 36 and the plate 23, and that while firmpressure'is exerted by the atmosphere to hold the printing plate 51 to the table and the design carrying sheet 5:2 to the printing plate, yet the air can travel along the surface of the negative and beneath the printing plate and thus secure and hold a strong and uniform atmospheric pressure through the entire area partly formed by the negative and printing plate.

The manner of operation of the device will be clearly understood from the foregoing, and it will be seen that the objects of invention are realized by means of the embodiment described and illustrated.

\Vhat I do claim as my invention and desire to secure by Letters Patent, is:

l. Frames having opposed sealing elements, a support carried by one frame, a flexible light transmitting sheet impervious to air adapted to be held between the sealing elements, and means through which air may be exhausted from between the sheet and support.

2. Frames having opposed sealing elements, :1 support carried by one frame, a flexible light transmitting sheet impervious to air adapted to be held between the sealing elements, means located between said sheet and the support and adapted to permit transverse travel of the air therebetween, and means through which air may be exhausted from between the sheet and support.

3. Frames having opposed sealing elements, a support carried by one frame, a flexible light transmitting sheet impervious to air adapted to be held between the sealing elements, a sheet pervious to air adapted to be positioned between the said support and impervious sheet and means through which air may be exhausted from between the impervious sheet and support.

4. An exposing table including in combination a support upon which is adapted to rest a plate having a light sensitive surface, said plate adapted to carry a flexible light transmitting design carrying sheet, a flexible light transmitting sheet impervious to air located above the support, means for sealthe edges of said impervious sheet to render.

the space between said sheet and said support air tight, a sheet pervious to air between the impervious flexible sheet and support, and means through which the air may beexhausted from said air tight space.

5. An exposing table including in combination a support upon which is adapted to rest a plate having a light sensitive surface, said plate adapted to carry a flexible light transmitting design carrying sheet, a flexible light transmitting sheet impervious to air located above the support, means for sealing the edges of said impervious sheet to render the space between the said sheet and said support air tight, means entering through said support and through which the air may be exhausted from said air tight space, and means permitting the air to travel beneath said plate. on the support to said exhausting means.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

HUGO C. KNUDSEN.

WVitnesses:

JOHN D. MORGAN, RosE MENK. 

